Polarization of the anterior-posterior (A-P) body axis in the nematode Caenorhabditis elegans occurs shortly after fertilization and before onset of the first round of mitosis. This polarization event occurs in close succession following the completion of meiosis by the oocyte chromosomes. Interestingly, both meiotic completion and axis polarization are triggered by cues from the sperm, although very few sperm-supplied factors have been identified. Recent studies have suggested that meiotic exit defects often correlate with defects in axis establishment, suggesting that these two processes may be developmentally linked. Despite this, little is known about how these events are temporally regulated in the cell or possible interrationships between the two. To investigate this problem, the scu-1 (sperm cue abnormal) gene will be studied in C. elegans. Mutations in scu-1 result in both a meiotic exit defect and a failure to polarize the A-P axis. In addition, the scu-1 gene product is contributed both maternally and paternally which may lead to a better understanding of paternally supplied proteins. To uncover the mechanisms by which scu-1 regulates meioitic exit and axis polarization, research will focus on three specific aims. 1) The role of scu-1 during meiotic exit will be examined by testing the role for scu-1 in MAPK and MPF deactivation after meiosis, and by dissecting the maternal and paternal contributions of SCU-1 during meiosis. 2) The molecular identity of the scu-1 gene and the subcellular localization of the protein will be determined through molecular cloning and antibody production and staining 3) SCU-1 interacting proteins will be identified though genetic suppressor screens and a genome-wide RNA interference screen for enhancers. These studies should provide insights into the mechanisms controlling the coordination of the cell cycle and polarity in the early embryo.